Cardiac CT
CT Angio of the Coronary Arteries
What is a CT Coronary Angiogram?
Advances in CT technology permits the clear visualization of the coronary on a high-end multi-detector CT (MDCT) scanner. This new technology allows the compilation of exquisite images depicting the coronary arteries without the associated risks of the older invasive procedures.
As this examination is extremely specialized, our staff undergoes special training to be able to scan the heart as well as process the images, to create quality diagnostic angiographic and 3D images of the heart and coronary vessels.
It is imperative that the patient fully co-operates with instructions as this will impact the outcome of the scan.
What can I expect?
A cardiology workup is done by your cardiologist, and you may be given a Betablocker to take the night and morning before your examination to stabilize your heartrate.
When you arrive in the CT department, your heart rate and blood pressure will be monitored. If your heart rate is above 80bpm an additional beta-blocker tablet will be given after consultation with the radiologist and your cardiologist. After 45-60 minutes, your heart rate is monitored again and if it has slowed sufficiently, the radiographer will start the scan. If your heart rate is still not optimal, the cardiologist is consulted and your scan might need to be rebooked after your heartrate has stabilized.
Your full co-operation is critical to ensure the success of the scan. Special breathing instructions will be given during the scan, and a breathing exercise will be performed a number of times to monitor the heart rate during a breath hold. An intravenous line will be inserted for the contrast injection. A vasodilator tablet called TNT (Isosorb dini5) is placed under your tongue just before the scan to dilate the cardiac vessels for the scan. This may cause a slight headache, which resolves rapidly, as well as a strange taste in the mouth.
Two scans are performed. The first will identify any calcified plaque in the coronary arteries. The number and size of these plaques are used to calculate the Agatston Calcium score, which quantifies the relative risk for cardiac disease. This score will determine whether the second scan can be done.
The second scan uses the intravenous contrast agent and utilizes special technology that enables the scanner to acquire images at the same instant in every heartbeat, creating an angiographic image without movement. By injecting a reduced amount of Iodine-based contrast media followed by saline, a bolus of the contrast medium is concentrated in the arterial system of the heart at the time of the scan.
This allows accurate diagnosis of pathologies.
What can be diagnosed on this CT?
Among others, the following conditions may be diagnosed:
• Abnormal coronary artery origins or courses
• Narrowing/occlusion of the coronary arteries
• Patency of arteries after coronary stenting
If significant pathology is identified you may be referred for a conventional cardiac angiogram. The Cardiac CT Angiogram, however, remains a non-invasive, low-risk first investigation in patients at risk for cardiac disease.
How long does it take?
The total time spent in our department can be 1 – 2 hours.
After the scan, the post-processing is done with great care to ensure accuracy and the radiologist carefully reviews the images.
The images and a detailed report by our specially trained radiologist will be sent to your referring doctor, and you will receive a digital copy via email.
Special preparation for a CT of the Coronary Arteries:
As this examination is highly specialized, we rely on your co-operation.
Please advise the receptionist and radiographer of the following conditions at the time of booking the appointment so that precautions can be taken:
• Asthma
• Diabetes
• Renal disease
• All Allergies
• Pregnancy
• Heart disease
Please avoid intense activity, any caffeine and not smoke on the day of the scan.
What are the benefits and the risks?
Benefits:
• Cardiac CT for calcium scoring is a fast, convenient and non-invasive way of evaluating the presence of coronary artery disease that is present even in the event of the lack of symptoms.
• Cardiac CT is relatively quick and causes no pain.
Risks:
• Pregnant women should avoid having cardiac CT. If there is any possibility that you are pregnant you should inform the radiographer.
• A limited amount of radiation is given during this examination.
• Cardiac CT may show an abnormality that could require further tests.
• There is a small risk of allergic reaction to the iodine contrast medium that is administered. Please inform the radiographer of all allergies
• Normal kidney function is required before iodine contrast can be injected.
Who could benefit from having CT coronary angiography?
• Patients with atypical or non-anginal chest pain
• Patients with equivocal stress tests
• Asymptomatic patients with one or more of the following risk factors: smoking, high cholesterol, family history of heart disease, high blood pressure, overweight, diabetes, sedentary lifestyle or as determined by your cardiologist.